The "unilateral binding offer" with the French company is to acquire Bayer Garden in Europe and Bayer Advance in North America.
The two companies are both based in Lyon, France.
SBM has a large presence in the French home and garden market with biological and synthetic products, fertilisers and soils but has no presence in the UK.
Bayer Garden head Darren Brown said: "Potentially this is very good news for the Bayer Garden business both for retailers and the end consumer and employees because they have no presence in the UK."
He said the deal would be a building strategy investment rather than an equity investment.
He said the SBM range would compliment Bayer's range and Bayer's Baby Bio, Phostrogen and other brands would remain.
Brown said the deal would take eight or nine months to complete.